Poppet-style valves are typically used in gaseous and/or liquid fuel injectors and generally consist of flat metering plates that seal against one another when the valve is closed. In high pressure industrial applications, for example, high pressure fuel flows through the poppet-style valve, which creates flow forces around the metering plates as they open and close. A large internal combustion engine, especially in an industrial application, typically includes several poppet-style valves to regulate fuel flow into the engine's combustion chamber. In order to provide predictable and reliable engine output, all of the injectors in such a large internal combustion engine must have similar fuel discharge characteristics. Otherwise, large variations in fuel discharge may be experienced between the multiple injectors of the engine.
The nature of the seal between the metering plates generally requires the metering plates to have a flat surface. This flatness requirement drives the creation of a sharp, 90° edge at the outer perimeter of the metering plate. That is, the peripheral edge of the metering plate proximal to the sealing surface forms a 90° angle. Using conventional manufacturing techniques, achieving a perfectly sharp edge is difficult, and small deviations from sharp are produced under normal manufacturing tolerances. In a large engine, especially in light of the high fuel pressure, even relatively small deviations from sharp on a plate-to-plate basis affect the discharge characteristics between the various injectors. Indeed, the discharge coefficient of a metering plate is much more sensitive as the edge approaches sharpness. Put differently, the percentage change in discharge coefficient increases as a result of deviations associated with typical manufacturing tolerances the closer the edge gets to 90°.
Because of the difficulty in manufacturing metering plates having consistent dimensions and because such inconsistencies have a drastic effect on the discharge coefficient of conventional sharp-edge metering plates, a need exists in the art for a metering plate that overcomes these difficulties. Embodiments of the presently disclosed invention provide such a metering plate. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.